A data recorder, which records desired data using a laser on a disc medium functioning as a recording medium, such as an optical disc, usually includes a write strategy circuit. The write strategy circuit generates a timing signal for controlling the state of laser irradiation. One example of such a timing signal is a recording pulse, which is generated by pulse-modulating data subject to recording, for controlling the intensity and time of laser irradiation on a disc medium. The laser irradiation is carried out according to the recording pulse so that pits corresponding to the desired data in an optimal manner are formed on the disc medium.
A timing signal, such as a recording pulse, is generated, its unit being a time interval that is shorter than the cycle of a reference clock signal. The reference clock signal is a clock signal corresponding to the rotation mode of the disc medium and serves as a reference for the recording operation. The write strategy circuit generates a plurality of delay signals, each having a predetermined delay with respect to an edge of the reference clock signal. By using such delay signals, the write strategy circuit generates a timing signal, its unit being a time interval shorter than the cycle of the reference clock signal, for controlling the mode of laser irradiation.
In recent years, various disc media, such as CD-R (Compact Disc-Recordable), CD-RW (Compact Disk-Rewritable), DVD-R (Digital Versatile Disc-Recordable), and DVD-RW (Digital Versatile Disc-Rewritable), have appeared on the market. Under such circumstances, there has been a demand for versatile recording controllers and reproduction controllers for controlling recording and reproduction of data on plural types of disc media, such as a CD-R and a DVD-R. However, such recording controllers and reproduction controllers cannot be constructed without a substantial increase in their circuit scale.
The specification relating to control of the laser irradiation state differs for each type of disc medium. This enlarges the circuit scale of the write strategy circuit. To be more specific, the write strategy circuit generates a timing signal whose time interval differs depending on the specification for each disc medium. To this end, the write strategy circuit is required to include a separate delay circuit for each specification in order to generate a delay signal corresponding to each specification. This inevitably enlarges the circuit scale of the write strategy circuit.
The above-described problem is not limited to the write strategy circuit, but commonly occurs with any delay signal generator that generates, from a single input signal, a plurality of delay signals differing from one another in the minimum unit of delay amount.